diff --git a/src/core/cmap.js b/src/core/cmap.js
index 792c679df..83c0d7224 100644
--- a/src/core/cmap.js
+++ b/src/core/cmap.js
@@ -313,6 +313,14 @@ var BinaryCMapReader = (function BinaryCMapReaderClosure() {
   }
 
   function hexToStr(a, size) {
+    // This code is hot. Special-case some common values to avoid creating an
+    // object with subarray().
+    if (size == 1) {
+      return String.fromCharCode(a[0], a[1]);
+    }
+    if (size == 3) {
+      return String.fromCharCode(a[0], a[1], a[2], a[3]);
+    }
     return String.fromCharCode.apply(null, a.subarray(0, size + 1));
   }